Herbicidal method employing n, n-dialkyl-diphenylacetamides



3 120 434 HERBICIDAL Mimiop EMPLOYING N,N-DI- ALKYL-DIPHENYLACETAMIDES Albert Pohland, Indianapolis, Ind., assignor to Eli Lilly and Company, Indianapolis, Ind., a corporation of 5 Indiana N0 Drawing. Filed Sept. 9, 1960, Ser. No. 54,851

' 9 Claims. (CI. 71--2.6)

This invention relates to novel herbicidal compositions having broad though selective herbicidal activity and to herbicidal processesjemploying these compositions. More particularly, this 'invention relates to novel herbicidal processes employing compositions in which an N,N-dialiphatic-substituted diphenylacetamide is the herbicidally active ingredient.

In the past, two types of broad spectrum herbicides have been available. One of these comprises 2,4-dichlorophenoxyacetic acid and related compounds which are useful for killing dicotyledonous plants. The monocotyledonous plants, which include the grasses, are not greatly affected by this type of herbicide, but only by nonselective herbicides such as sodium arsenite, p-chlorophenyldimethyl 'urea, sodium chlorate, and ammonium sulfamate, all of which, effectively destroy all types of vegetation. Only a few compounds have been found which will destroy monocotyledonous plants such as grasses, preferentially to dicotyledonous plants, and still fewer compounds have been found which will destroy grasses and only certain classes of broad-leaf plants.

It is an object of this invention to provide compositions which are toxic both to grasses in either their germinating or mature stages and to broad-leaf weeds, but which are nontoxic for broad-leaf crop plants. It is a further object of this invention to provide novel compositions and processes which can eliminate both weed grasses and broad-leaf weeds selectively from crop plants such as tomatoes, potatoes, cabbage, tobacco, strawberries,. and their close relatives in the plant kingdom.

in fulfillment of the above and other objects, this invention provides a novel process and compositions for inhibiting the growth of weed grasses and broad-leaf weeds.

The novel process comprises applying to an area infested with weed seeds, seedlings and mature weed plants a herbicidal amount of a compound represented by the following formula:

wherein R and R are methyl, ethyl, n-propyl, isopropyl.

1 ethyl- (4-tolyl)phenylacetamide, N-methyl-N-n-propyl-(2,

4-dibromophenyl)phenylacetamidc, N,N-diallyl-(4-tolyl)- 4 chlorophenylacetamide, N,N-di-n-propyl-(2-chloro-4- tolyl)phenylthioacetamide, and N-allyl-N-n-propyl diphenylacetamide. As will be obvious to those skilled in 3,120,434 Parenisareb. 4, 1964 the art, other equivalent aromatic and chlorinated aromatic' groups can be substituted for the benzene rings, such being thienyl or chlorothienyl groups.

Compounds represented by the above formula are provided for use as pre-emergent selective herbicides in customary manner, such as sprays (preferably concentrates) spreadable granules, or wettable powders. The 'compounds are insoluble in water, and hence for the preparation of emulsion-type sprays or wettable powders, they should be formulated with a wetting agent or surfactant to obtain a useful dispersion.

, The novelprocesses of this invention comprise treating a soil area or locus infested with seeds, seedlings and/or mature weed grass plants, and broad-leaf weeds with a formulation containing a compound within the scope of the formula as the herbicidally active ingredient. Illustratively, crop areas which can be treated with the herbicidal compositions of this invention for the elimination of weed grasses and broad-leaf weeds include those areas in which members of the following plant families are growing: Solanaceae, Compositae, Cruciferae and Rosaceae. Such crop areas include tomato fields, potato fields, tobacco fields, rose gardens, sunflower fields, strawberry patches, and truck gardens where cabbage, peppers, radishes, cauliflower, and like plants .are being grown. Other areas from which weed grasses and broad-leaf weeds can be eliminated include gravel driveways or walks, road shoulders, and the like.

Compositions containing the herbicidally active compound are conveniently distributed by spray or by other suitable spreader to the area to be treated, preferably at a rate of about /2 to about 16 lb. of active ingredient per acre. When a spray is used as the medium of distribution, the herbicidal compositions are preferably applied at a rate of about 1 to 4 lb. of active ingredient per acre. However, if the herbicidal compositions are applied to the particular area in a granular form from which the active herbicide is slowly released so that there is a more prolonged herbicidal action, a greater amount of active material per acre is generally employed than when a spray is used, this greater amount being in the range of 2 to 8 lb. per acre of active ingredient.

Seedlings, germinating seeds, and mature plants of many varieties of grasses are killed by the above treatment process, such including both undesirable grasses such as the crabgrasses (Digimria srmguinalis and Digitaria ischaemum); green and yellow foxtails (Setaria viridis and Setaria Iutescens); Johnson grass (Sorghum helepense); goose grass (E/eusine indica); sandbur (Cenchrus pauci florus); witchgrass (Panicum capillar'e), and the like, as well as the desirable grasses such as Bermuda grass (Cynodon dactylzm); Kentucky bluegrass (Paa pratensis); fescues (Festuca sp.); orchard grass (Dactylis glomernta); and red top (Agrostis alba).

The broad-leaf weeds which can be eliminated from infested areas by the processes and compositions of this in- Thus,

the

y the Suflicient soil was added to cover the entire flat.

the weed seeds were covered to a depth of about 6 mm. and the crop plant seeds were covered to a depth of about 3 cm.

In assaying the effect of the compositions as preemergent herbicides, a fiat prepared as above, taken either on the day of planting or on the next day, was placed in a chamber equipped with a turntable and an air exhaust. The herbicidal composition, whether it was a spray-type with a modified De Vilbiss atomizer hooked to an air source. Twelve and one-half ml. of the composition under test were applied to each fiat either on the day of planting or the succeeding day. For measuring the effiherbicides, the same experimental setup was used except that the flats were sprayed after nine to twelve days in a greenhouse, the length of growing time depending upon the season and light intensity. Injury ratings and observato twelve days after treatment. The injury rating scale used was as follows:

no injury 1--slight injury 2-moderate injury 3severe injury 4death average value was calculated for the injury rating.

Tables I and II set forth the results of testing N,N- dialiphatic-substituted diphenylacetamides within scope of the above formula as pre-emergent and post- In each table, column 1 gives the name of the compound under test; column 2, the rate in pounds per acre at which the compound is applied to the test fiat; and the remaining columns, the injury to the particular plant seeds or seedlings as measured b Table I emulsion or a wettable powder, was applied to the fiat cacy of the herbicidal compositions as post-emergent tions as to type of injury were made in either case eleven 35 emergent herbicides.

l- 30 When more than one determination was carried out, an rush Mature EXAMPLE 1 The following experimental procedure was used to demonstrate the efficacy of the compositions of this invention in killing germinating and seedling grasses with- 5 growth of -leaf plants: A soil was pretogether in a cement mixer.

one species to each section: foxtail (millet), 100 mg.; broad-leaf mustard, 50-75 mg.; rough pigweed, 30-50 mg; and large crabgrass, 350-400 mg. 40 foregoing scale.

INJURY RATING ON PRE-EMERGENT TREATMENT As might be expected, broad-leaf weeds are unaffected by the herbicidal action of the compositions of this invention to the extent that such weeds belong to the families Solanaceae, Compositae, Cruciferae, and Rosaceae, enumerated above.

The herbicidal compositions of this invention do not affect the growth of crop plants other than the members of the four families of broad-leaf plants set forth above. For example, corn, cotton, alfalfa, flax, sorghum and soybean seedlings are not affected by the application of a compound represented by the above formula in an amount suflicient to destroy germinating grasses. cotton and sorghum plants are also unaffected by application of an amount of one of the compositions of this invention sufficient to eradicate weed grasses and broadleaf weeds from the crop-growing area.

The following examples more clearly illustrate the invention. It is to be understood, however, that such examples are illustrative only, and are not intended as limitations upon the scope of the invention.

out affecting the germination of seeds and the seedlings of selected broad pared consisting of one part masonry sand and one part shredded top soil blended One gallon of this soil was placed in a x 35 cm. vanized flat and was patted down with a bench b until level. A three-row marker was used to make 2 /2 cm. deep furrows in approximately two-fifths of the flat. Crop seeds consisting of four kernels of corn, five cotton seeds and five soybean seeds were placed in these furrows. A four-row template was then placed on the remaining soil and the indicated amounts of each of the followin seeds were planted Ht 2 1LU O 2 3 a mm L 0 3882111310032553210321533221038223221 3221 w ZLLL 2 0 0 L .m P m 8 U0U0 Ono- 000 90025112.11150100002101 5100 m L00 0 L 0 1 s .w .n m 444 67133 0725544 a444544453344324332 4432 m &2 3 00 a 3 b a r C n 1n -000000000000000000000100000000 000 0000 m 0 D V- o ab n 200000000000000010000001000000000000 000 m 0 t 0 C 6400000000000 000 0000000000000 00 0000 m L00 0 C 832l AA84218421842184218421' VA840u1842-1 8421 l 1- I./ LA

u n n a n u u n n n n n n c c n a m u n m m u u m 0 m u .M 0 m n d m m u e t d m l d m .1 u m a v. i m m e a a l n m m m d d m w. m m n d m M m m m a m e n. n m 1 a m a. h m m u u a v. W. t n u. i o l n n m m e i d n m. v. M n. a a .0 l l l m m p w w. m m y w m n .1 m m. d m m 0 l w m am .1 i h h V. t D. 3.1. d v. w n. P h n. o (l l i 1 0a 5 H v. m w d a m m 4 Fa. m n. m. w. w. N N mm. c o H N L. 1 n m m n a v. v. m .1 e 1 h h 1 4 m m m m m u a an K a m m b. N N N N N N N N N Fox tall n420- 2"ml-12210 02 002200 Each of the In Tables III and IV, column ssonTED BROAD-LEAF PLANTS 130 I022 122 B no 0 u 1 m m 120 0111 111 mm mm 2 o o 00 L0 2 0 0 U0 0 u n n p l. 010 .0000 .000 d 1 a 8 231 0133 023 I v.m mm 4. 120 0111. 022 mm o V. 030 .0200 011 Nu 2 n u 0 N... n H .m 010 .0000 .001

Soil was placed in the band and pressed ulflvzlv ovl2.12221320103200 000 The planted boxes were placed in a greenhouse,

' Table III AND GRASSES N,N-dlmethyl (liphenylueetarnlde Tables III and IV set forth the results of tests carried with bottoms.

down to an even depth. Small seeds were planted by covering them with up to 6 mm. of soil, whereas large seeds, such as beans, corn, cotton, sorghum, and the like, were planted 12 mm. or more below the surface of the soil.

anc by judiciously regulating the planting time, plants of different types were readied for treatment at the same days) in the time required for seeds of the various plants to germinate and for seedlings to grow to a suitable size. Flats containing one box of each of the species under test were assembled and were sprayed with the test material by the procedure described in Example 1.

out as described above for three compounds: N,N-dimethyl diphenylacetamide, N,N-diethyl diphenylacetamide, and N,N-diallyl diphenylacetamidc.

compounds had previously shown outstanding activity against weed grasses in pre-emergent testing, as shown in Table I. In Tables III and IV, the same injury ratings are used as were used in Tables I and II, and when more than one test was carried out, the injury rating given was 1 gives the name of the plant used; column 2, the variety; column 3, the results of treatment at 0.5, 1, 2 and 4 pounds per acre of N,N-dimethyl diphenylacetamide; column 4, the results of treatment at 1, 2, 4 and 8 pounds 5, the results of treatment at l, 2, 4 and 8 pounds per acre of N,N-diallyl diphenylacetamide.

Cotton Soybean Crubgrass Mustard ligwcod time despite the wide differences (seven to twenty-one expressed as an average.

per acre of N,N-diethyl diphenylacetamide; and column Variety Cum The com- 45 Red Table II-Continued Acre Plant yl 2,4'-diehloro-diphenylaeeta 1uule. r

In the above trials, the compound under test was formu- This dispersion was entirely satisfactory for In a second procedure the compound was dissolved in one volume of acetone, and the acetone solution was diluted with nineteen volumes of water con- EXAMPLE 2 Further testing of three specific compounds represented by the above formula was carried out against a broader spectrum of plants than was included within the preliminary test. Among these plants were broad-leaf, ornamen- In the pre-emergent test the seeds were sown in flats, as described in Example 1, and were treated with the However, since three weeks time is required for certain slow-growing species, observations were made up to twenty-one days after treatment.

In the post-emergent extended test the various species of plants were seeded in three-inch square wood bands INJURY RATING ON PRE-EMERGENT TREATMENT or A lated as a spray by one of the following procedures. one method the particular compound was wetted by grinding in a mortar with one part of polyoxyethylene sorbitan monolaurate. Five hundred parts of water were added slowly to the resultant creamy paste to give an aqueous dispersion with a surfactant concentration of 0.2 percent.

spray application.

taining 0.1 percent of polyoxyethylene sorbitan monolaurate.

tal and crop plants, and certain crop grasses.

pounds were tested on the plants against both the preemergent and post-emergent growth stages.

formulated compound the following day. Observations as to injury rating were made in most cases fourteen days after treatment.

..- Ranger.....-

.eS e

nmmm u H 5 wrhm a g m IO hu I ll 0 m o AC JNRSSST Table IV INJURY RATING ON POST-EMERGENT TREATMENT OF ASSORTED BROAD-LEAF PLANTS AND GRASSES N,N-dirnethyl N,N-diethyl N,N-diallyl diphenylacetamide diphenylacctnmide diphcnylacctamide Plant Variety 0 1 1 0 l 1 2 0 1 1 2 0 1 l 2 1 2 2 2 0 1 2 2 0 0 1 1 1 l 1 1 0 1 l 1 0 0 1 1 0 0 1 1 0 0 0 1 Ragweed (oinmon 0 0 0 1 0 0 1 1 0 0 1 1 Smartivec'd Pennsylvania 0 1 2 2 1 1 2 3 0 1 1 1 Sorghuin 1 1 1 2 0 0 0 1 0 0 0 0 Sugar Beets 0 0' 1 1 'lomatocs. -0 0 1 1 0 0 l l 0 0 0 l I n" 0 0 1 2 2 2 2 2 1 l 2 2 Wild Oats... 0 1 2 2 0 1 -0 1, 0 1 1 1 EXAMPLE 3 plot as determlned by this test. In the table, column 1 N,N-dimethyl diphenylacetamide possesses outstanding activity against grassesin pre-emergent testing and has a notable lack of phytotoxicity for broad-leaf plants belonging to the families Solanaceae, Compositae, Cruciferae and Rosaceae in post-emergent testing, as set forth in Tables I-IV. The compound was submitted to a series of field trials in various formulations.

(l) Granular formulation.500 g. of N,N-dimethyl diphenylacetamide were slurried with 2.2 kg. of phenyl Cellosolve, and the resulting mix was warmed to approximately 40 C. with slight agitation until there were no visible solids present. The solution was then sprayed at the elevated temperature, under a pressure of about 58 p.s.i., upon 7.3 kg. of /60 mesh calcined attapulgite clay. The granules were tumbled throughout the impregnation to achieve homogeneity, and tumbling was continued until a homogeneous, dry flowable product was obtained. The resulting product contained 5 percent by weight of N,N-tlimethyl diphenylacetamide, 22 percent solvent, and 73 percent clay granules.

(2) Wettablc p0wder.-One pound of N,N-dimethyl diphenylacetamide was thoroughly dry-blended with 136.2 g. of a finely-divided synthetic hydrated silica,

' 32.4 g. of sodium lignosulfonate, and 25.9 g. of sodium N-methyl-N -oleoyl taurate. This mix was then passed once through a hammer mill to yield a powder with maximum particle size of approximately 100 mesh. The final composition contained 70 percent N,Nrdimethyl diphenylacetamide, 21 percent synthetic hydrated silica, 5 percent dispersant, and 4 percent wetting agent.

(3) Emulsifiable c011ccntrat.-An emulsifiable concentrate containing 1.25 lb. per gal. was prepared by dissolving l3 g. of N,N-dimethyl diphenylacetamide in a two-component solvent containing three parts xylene to two parts phenyl Cellosolve. A complex blend of alkylarylsulfonate and non-ionic emulsifiers was added to this solution as the emulsifying agent. The final composition of this liquid concentrate was, by weight, 15.3 percent N,N-dimethyl diphenylacetamide, 41.3 percent xylene, 35.4 percent phenyl Cellosolve, and 8.0 percent emulsifier.

Table V gives the injury ratings to plants in the test 75 gives the rate of application of N,N-dimethyl diphenylacetamide in pounds per acre; column 2, the injury rating against grass weeds; column 3, the injury rating against broad-leaf plants; column 4, the injury rating against tomatoes. The injury ratings are the same as those used in Tables IIV.

Table V INJURY RATINGS with only minimal damage to the tomato plants. At the same time, the compound had excellent herbicidal action against susceptible broad-leaf weeds. Jimson weed, a member of the same plant family as the tomato, heavily infested the test area, and since its growth was not affected by N,N-dimethyl' diphenylacetamide, the damage rating against broad-leaf weeds was lower than would have been expected with a more nearly normal weed crop. Furthermore, it was found that the dry weight of tomato plants was increased in areas in which the weed grasses and a majority of broad-leaf plantshad been eliminated by the application thereto of N,N-dimethyl diphenylacetamide. This increase amounted to 95 percent for plots treated at the 4 lb.-per acre application rate of N, N-dimcthyl diphenylacetamide, 45 percent at the 8 lb.- per-acre application rate, and 35 percent at the 12 lb.-peracre application rate.

Other compounds within the scope of the present ,invention can be formulated to yield the herbicidal compositions of my invention by following the above procedure, it being understood that the ratio of dispersants and wetting agents may be required to be varied, depending upon the physical properties of the particular compound.

EXAMPLE 4 In 'a second field trial, N,N-dimethyl diphenylacetamide was applied to an established cultivated field of tomatoes using both a granular and a wettable powder formulation prepared as indicated above. N,N-dimethyl diphenylacetamide was consequently applied post-emergent to the tomatoes but pre-emergent to the weed population.

Table VI gives the percent control of grasses and broadleaf weeds. for different application rates of N,N-dirnethyl diphenylacetamide'eithcr as a wettable powder formulation or in a granular formulation.

. Wcttable Powder 11 Table VI Percent Control R51 to Lb./Aere Formulation Broad-loaf Weeds G rasses Granular Untreated As before, Jimson weed was a major broad-leaf weed present and the weed control percent was therefore somewhat less than would have been expected with a more nearly normal weed population.

EXAMPLE 5 In a further field trial of N,N-dimethyl diphenylacetamide, the compound was applied as a wettable powder formulation to a field in which sorghum, field corn, and Johnson grass seeds had been planted, but prior to their germination.

Table VII gives the results of this test, using the same injury ratings as were used here previously.

Table VII APPLICATION OF N,N DIME'IIlYL DIPIIENYLACET- AMIDE AS A PRE-EMERGENI HERBICIDE A similar field trial was carried out in which three legumes- -alfalfa, birds-foot trefoil, and Korean lespedeza-were planted along with large crabgrass as a weed grass, and N,N-dimethy1 diphenylacetamide was applied to the area pre-emergent as a wettable powder formulation. Table VIII gives the injury ratings to the plants using the usual scale.

Table VIII APPLICATION OF N.N-DIMETl'IYL DIPIIENYLACET- AMIDE PRE-EMERGENT TO LEGUMES Average Injury Ratings (9 days) Rate LbJAcre Altalta Btrds-toot Korean Largo Trctoil Lespedcza Crabgrass 0 1 0 3 0 0.5 0 4 I l 0. 5 4 l 1. 5 1 4 2 1. 5 l 4 The compounds of this invention are relatively nontoxic for mammals; for example, the median lethal oral dose of N,N-dimethyl diphcnylacetamidc for mice was about 700 mg./kg., and the median lethal doses intrapcritoneally or subcutaneously were approximately 800 to 1,000 mg./kg.

The compounds which are the herbicidally active ingredients in my novel compositions and processes are prepared, as illustrated in the following paragraphs, by reacting diphenylacetyl chloride or a suitably substituted diphenylacetyl chloride with a secondary amine in the presence of a base. The base is preferably employed in at least equimolar ratio to the diphenylacetyl chloride in order to take up the liberated hydrogen chloride. For this purpose, the base may be merely an additional quantity of the secondary amine. The diphenylacetyl chlorides are prepared by hydrolyzing the corresponding diphenylacetonitrile, prepared by the method of Jack Mills described in US. Patent No. 2,447,419, and subsequently reacting the hydrolytically produced acid with thionyl chloride.

The following is an illustration of the Mills procedure and subsequent hydrolysis:

53 g. of benzaldehyde are mixed with 72 g. of fluorobenzene and 25 ml. of hydrogen cyanide. The reaction mixture is cooled to about 0 C., is saturated with boron trifiuoride, and is stirred for about 16 hours at ambient room temperature. It is then washed twice with -ml. portions of water, twice with IOO-ml. portions of aqueous sodium bisulfite solution, and again twice with 100-ml. portions of water. The organic layer is separated and dried, and the volatile substituents are evaporated in vacuo. Distillation of the residue yields (4-fluor0phcnyl)- phenylacetonitrile, which boils at about 109 C. at a pressure of about 0.05 mm. of mercury. It melts at about 3941 C. and has an index of refraction, n =l.560.

10.5 g. of the (4-fiuorophenyl)phenylacetonitrile are heated at refluxing temperature with 35 g. of potassium hydroxide dissolved in 250 ml. of a 1:1 ethanol-water mixture. The reaction mixture is cooled and is extracted with 250 ml. of ether to remove any unreacted starting material and any (4-fiuorophenyl)phenylacetamid also formed in the reaction. The reaction mixture is acidified with 12 N hydrochloric acid, and the (4-fiuorophenyl)- phenylacetic acid, which is insoluble in the acid, precipitates. The precipitate is collected by filtration. (4-fluorophenyDphenylacetic acid thus prepared melts at about l06-l07 C. after recrystallization from aqueous ethanol.

Preparation of N,N-Dimethyl Diph'enylacetamide 9.66 g. of diphenylacetyl chloride were dissolved in 25 m]. of benzene. A solution of 5.68 g. of dimethylamine in 50 ml. of benzene was added dropwise to the acid chloride solution. After the addition had been completed, the reaction mixture was heated at refluxing temperature for an additional 2 hours. The reaction mixture was cooled, and sufficient chloroform was added to render the mixture homogeneous. The organic layer was washed with successive IOO-ml. portions of 10 percent hydrochloric acid, water, saturated sodium bicarbonate solution and water, and was then dried. The solvents were removed by evaporation in vacuo, and the residue, comprising N,N-dimethy1 diphenylacetamide formed in the above reaction, was recrystallized three times from a mixture of benzene and hexane and twice from a mixture of ethyl acetate and hexane. N,N-dimethyl diphenylacetamide thus prepared melted at about 128 C.

AnaIysis.-CalC.: C, 80.29; H, 7.16; N, 5.85. Found: C, 80.47; H, 6.95; N, 5.86.

The following N,N-di-aliphatic-substituted diphenylacetamides were prepared from diphenylacetyl chloride and the apropriate secondary amine by the procedure described above. Pertinent data are given in Table IX.

I Table IX MISCELLANEOUS DIPHENYLACETAMIDES Product Amine N,N-(li-n-propyl diphcnylacetnmldc... di-n-propylaminc N,I\'-dl-isopropyl diphenylacctamidc di-isopropylnmine N,.\*-\li-allyl diphenylacetatnide... di-allylamine..-

N ,N-(liuthyl riiphenlacrtamidyc. dicthylamine...

N; ethyl-N-isopropyl(lliphenaeetamyide. inothylisopropylamin -mcthyl-N-n-propyl (liphenylaeetamide N-ethyl-N-n-propyl diphenylacetamide- N'-ethyl-N-isopropyl diphenylacetnmide N-allyl-N-cthyl dipohnylacetamide. N-allyl-N-methyl diphenylaeotamid N-uthyl-N-methyl diphenylacetamide...

- allylethylamine. allylnicthylamine.

ethylmethylamine Analysis, N Product M.P.,

Cale. Found 4. 80 4. 34 5. 24 4. 97 5. 24 5. 30 5. 24 4. 2i 4. 9s 4. 72 4. 98 5. ll 5. O1 4. 92 v 28 5. 38 81-85 5. 53 5. 53

*Bclow ambient room temperature.

(Talc; C, 81.31, H, 8.53; Found: C, 81.43; H, 9.00.

Heavy viscous oil distilling at about 0.1 mm. Hg.

Purified by distillation.

Preparation of N ,N-Dimethyl (p-Chlorophenyl)- Phenylacetamide 10 g. of (p-chlorophenyl)phenylacetic acid were heated at refluxing temperature with ml. of thionyl chloride for about 1 /2 hours. removed by evaporation 'in vacuo, and the (p-chlorophenyl)phenylacetyl chloride thus prepared was poured Following the foregoing procedure, (3,4-dichlorophenyl)phenylacetyl' chloride, prepared by treating the corresponding acid with thionyl chloride, was poured into an excess of a 25 percent aqueous dimethylamine solution. The product was extracted and purified by the procedure of the foregoing preparation, the recrystallization being from dilute ethanol. The N,N-dimethyl (3,4- dichlorophenyl)phenylacetamide thus perpared melted at about 94-95 C.

A'naIysis.Oalc.: N, 4.55; Found: N, 4.36.

Preparation of N,N-Dimethyl (2,4-Dichl0rophenyl)- Phanylacetamide Following the previously described procedure, (2,4 dichlorophenyl)phenyl-acetyl chloride, prepared by reacting the corresponding acid with thionyl chloride, was poured into 10 ml. of a 25 percent aqueous dimethylamine solution. Tlfte N,N-dimethyl (2,4-dichlorophenyl)- phenylacetamide thus formed was purified by the previously described procedure and melted at about 105- 106 C. after recrystallization from aqueous ethanol.

Analysis.-Calc.: N, 4.55. Found: N, 4.86.

Preparation of N,N-Dimelhyl 2,4'-Dichl0r0- Diphenylacetamide Following the previously described procedure, 2,4'-dichloro-diphenylacetyl chloride, prepared from the corresponding acid by the reaction of thionyl chloride, was poured into an excess of a 25 percent aqueous dimethylamine solution. The N,N-d.imethyl 2,4'-dichloro-diphen.- ylacetamide thus formed was purified by the previously described procedure and melted at about 58-60 C. after a two-fold recrystallization from a benzene-hexane solvent mixture.

The excess thionyl chloride was 2 Analysis.-Calc.: N, 4.55. Found: N, 4.28.

Preparation of N,N-Dimethyl (4-Fluor0phenyl)- Phenylacetamide Following the previously described procedure, (4-

fluorophenyl)phenylacetyl chloride, prepared by reacting the corresponding acid with thionyl chloride, was poured into an excess of a 25 percent aqueous dimethylamine solution. The N,N-dimethyl (4-fiuorophenyl)phenylacetamide thus formed was purified by the previously described procedure and melted at about 90-91" C. after recrystallization from aqueous ethanol.

AnaIysis.Calc.: N, 5.44. Found: N, 5.48.

Preparation of N,N-Dinzethyl (3-T0Iyl)Phcnylacetamide Following the previously described procedure, (3- tolyl)phenylacetyl chloride, prepared by reacting the corresponding acid with thionyl chloride, was poured into an excess of a 25 percent aqueous dimethylamine solution. The N,N-dimethyl (3-tolyl)phenylacetamide thus formed was isolated by the previously described procedure and was purified by distillation; boiling point=144-146- C. at a pressure of about 0.1 mm. of mercury.

AnaIysis.--Calc.: N, 5.53. Found: N, 5.60.

Preparation of N,N-Dimethyl Diphenylthioacetamide A reaction mixture composed of 47.8 g. of N,N-di methyl diphenylacetamide and 24.4 g. of vphosphorus pentasulfide dissolved in 200 ml. of pyridine was stirred at refluxing temperature for about 2 hours, after which time the hot reaction mixture was slowly poured into water maintained at about C. The mixture was kept at ambient room temperature for about 16 hours, and a precipitate of N,N-dimethyl diphenylthioacetamide formed in the above reaction was collected by filtration. Recrystallization of the precipitate from ethanol followed by a recrystallization from a benzene-hexane solvent mixture yielded N,N-dimcthyl diphenylthioacetamide melting at about -127 C.

AnaIysis.--Calc.: C, 75.25; H, 6.71; N, 5.49. Found: C, 74.70; H, 6.54; N, 5.22.

I claim:

1. A method for inhibiting the growth of plants of the class of weed grasses and broad-leaf weeds, said plants being in any stage of development from seeds to mature plants, which comprises applying to an area containing plants of said class a herbicidal amount ofa compound represented by the following formula:

wherein R and R are members of the group consisting of methyl, ethyl, n-propyl, and :isopropyl; R is a member 15 of the group consisting of hydrogen and chlorine; R is a member of the group consisting of methyl and halogen; n is selected from the group consisting of 0, 1, and 2; and Y is a member of the group consisting of oxygen and sulfur.

2. A method for inhibiting the growth of weed grasses and broad-leaf weeds which comprises applying to an area infested with weed seeds and weed plants a herbicidal amount of a composition containing an inert diluent and as a herbicidally active ingredient a compound represented by the formula:

wherein R and R are members of the group consisting of methyl, ethyl, n-propyl. and isopropyl; R is a member of the group consisting of hydrogen and chlorine; R is a member of the group consisting of methyl and halogen; n is selected from the group consisting of 0, 1. and 2; and Y is a member of the group consisting of oxygen and sulfur.

3. A method for inhibiting the gowth of weed grasses and broad-leaf weeds which comprises applying to an area infested with weed seeds and weed plants an amount of about V1 to about 16 lbs. per acre of a herbicidally active compound represented by the formula:

wherein R and R are members of the group consisting 16 of methyl, ethyl, n-propyl, and isopropyl; R is a member of the group consisting of hydrogen and chlorine; R is a member of the group consisting of methyl and halogen; n is selected from the group consisting of 0, l, and 2; and Y is a member of the group consisting of oxygen and sulfur.

4. The method of claim 3 wherein N,N-dimethyl diphenylacetamide is the herbicidally active compound.

5. The method of claim 3 wherein N,N-diethyl diphenylacetamide is the herbicidally active compound.

6. The method of claim 3 wherein N-cthyl-N-methyl diphenylacetamide is the herbicidally active compound.

7. The method of claim 3 wherein N,N-dimethyl (3- tolyl(phenylacetamide is the herbicidally active compound.

8. The method of claim 3 wherein N,N-dimethyl (2,4- dichlorophenyl)phenylacetamide is the herbicidally active compound.

9. The method of preventing germination of seeds and controlling growth of plants which comprises contacting said seeds and plants with a herbicidally effective amount of N,N-dialkyl-a,a-diphenylaeetamide wherein alkyl is from 1 to 3 carbon atoms, inclusive.

References Cited in the file of this patent UNITED STATES PATENTS Jones Dec. 10, I946 Lemin July 10, 1962 OTHER REFERENCES 

1. A METHOD FOR INHIBITING THE GROWTH OF PLANTS OF THE CLASS OF WEED GRASSES AND BROAD-LEAF WEEDS, SAID PLANTS BEING IN ANY STAGE OF DEVELOPMENT FROM SEEDS TO MATURE PLANTS, WHICH COMPRISES APPLYING TO AN AREA CONTAINING PLANTS OF SAID CLASS A HERBICIDAL AMOUNT OF A COMPOUND REPRESENTED BY THE FOLLOWING FORMULA: 